The invention concerns an air-flow meter for milking machines. The meter comprises an enclosed housing with a connection to a line that is to be tested for flow and pressure. The housing has an air-intake mechanism with a variable cross-section.
A milk-flow meter of this type is known from German OS 1 757 838. It measures the output of a vacuum pump, a component of the machine, subject to various operating conditions. These measures must be repeated at various intervals, and their results must comply with domestic regulations in various countries.
The air-intake mechanism in the known meter consists of calibrated bores and of rotating disks that block them off. Since the disks are subject to considerable pressure, they are difficult to rotate. Furthermore, only discontinuous adjustments can be carried out, and no interpolations are possible. Finally, the bores can clog up and contaminate the results.